KR101354303B1 - Display unit - Google Patents

Abstract

A display device having a limited viewing angle and improved front luminance is provided. The display device is provided opposite to the display element and the display element, and has an incidence surface on the side facing the display element, an emission surface on the side opposite to the display element, and a reflection surface on the side surface. It includes a light guide portion having a cross section widening toward the exit surface.

Viewing angle, display device, brightness, light guide

Description

Display unit {DISPLAY UNIT}

1 is a diagram illustrating a configuration of a display device according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating a modification of FIG. 1. FIG.

FIG. 3 is a view for explaining a condition in which light which is not reflected by the reflective film and goes directly into the air is emitted within an angle α.

4 is a view for explaining a relationship between the maximum angle u ₁ of the light incident on the incident surface and the maximum angle u ₂ of the light emitted from the exit surface after being reflected at least once by the reflective film.

FIG. 5 is a view for explaining a condition that light emitted to the air after being reflected at least once by the reflective film is emitted within an angle α.

FIG. 6 is a diagram illustrating an illumination analysis result by the light guide unit illustrated in FIG. 1. FIG.

FIG. 7 is a perspective view illustrating an arrangement of a light emitting point and a light receiver used in the illumination analysis of FIG. 6.

FIG. 8 is a perspective view illustrating a configuration of the light emitting point illustrated in FIG. 7.

It is a figure which shows the illumination analysis result when the side surface of a light guide part is perpendicular.

FIG. 10 is a perspective view illustrating a configuration of a light emitting point used in the illumination analysis of FIG. 9.

11 is a cross-sectional view illustrating a specific example of the display device illustrated in FIG. 1.

FIG. 12 is a cross-sectional view illustrating a configuration of the organic light emitting element shown in FIG. 11.

13A and 13B are cross-sectional views illustrating a method of manufacturing the display device shown in FIG. 11 in the order of steps.

14A and 14B are sectional views showing a process following FIGS. 13A and 13B.

15 is a cross-sectional view illustrating a process following FIG. 14A and FIG. 14B.

<Explanation of symbols for the main parts of the drawings>

10: drive board

11: TFT

12: planarization layer

20: display element

20R, 20G, 20B: organic light emitting device

21: first electrode

22: insulating film

23: organic layer

23A: hole injection layer

23B: hole transport layer

23C: light emitting layer

23D: electron transport layer

24: second electrode

30: sealing substrate

31: phase difference plate

32: polarizer

40: middle layer

41: adhesive layer

50: light guide

51: entrance face

52: exit surface

53: side

54: reflecting film

[Patent Document 1] Japanese Patent Laid-Open No. 2003-303677

The present invention includes a patent object related to Japanese Patent Application No. 2006-067550, filed with the Japan Patent Office on March 13, 2006, the entire contents of which are incorporated herein by reference.

The present invention relates to a display device suitable for a mobile device.

Displays mounted on mobile devices are required to display high-quality images with high visibility while keeping the battery life as long as possible. However, these two demands are usually opposed. That is, although it is necessary to improve brightness in order to show visibility, this results in an increase in power consumption. As the power consumption increases, the duration of the battery becomes shorter. Otherwise, the weight of the battery becomes heavy for a long time operation, and the merchandise of the mobile device is significantly reduced.

As mobile devices are often used in crowded places outdoors, there is a growing tendency to worry about others looking into the screen. For that reason, intentionally limiting the viewing angle of the display has become an added value. For example, it has become popular to attach a film that restricts the viewing angle to the screen of a mobile phone.

However, in current liquid crystal monitors, light emission always occurs at a constant intensity from the backlight. Therefore, this viewing angle limitation does not result in reduction of power consumption. Moreover, the fall of visibility by sticking a film is also unavoidable.

In addition, in the related art, self-emitting devices such as EL (Electro Luminescence) devices and Plasma Display Pannel (PDP) devices have been proposed. That is, visibility is improved by providing a partition wall in the transparent substrate and diffusing and reflecting the light emitted from the light emitting layer at an angle larger than the critical angle by the partition wall (see Patent Document 1, for example). However, since such a conventional partition is formed perpendicular to the light acquisition surface, it is difficult to limit the exit angle of the light diffused and reflected by the partition. Therefore, it is also difficult to increase the brightness in the front direction (hereinafter, "front brightness") with respect to the light extraction face.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide a display device capable of limiting the viewing angle, increasing convenience and improving front brightness.

The display device according to the embodiment of the present invention is provided with a display element and a display element facing each other, an incident face on the side facing the display element, an exit face on the side opposite to the display element, and a reflection surface on the side surface thereof. and a light guiding part having a reflecting face and having a cross section widening from the incidence surface toward the emitting face.

In the display device according to the embodiment of the present invention, since the cross section of the light guide portion extends from the incident surface toward the exit surface and the side surface is the reflective surface, even if the total amount of light emission is the same, the emission angle range is It can narrow, and light is concentrated in the front direction with respect to an emission surface. Therefore, the viewing angle is limited and the front brightness is also improved.

According to the display device according to the exemplary embodiment of the present invention, the light guide portion has a cross section extending from the incident surface toward the exit surface, and the side surface is formed of the reflective surface. Accordingly, the viewing angle is limited by limiting the acquisition direction of the light, and the front brightness can be improved. As a result, it is especially suitable for the use which needs to ensure the privacy of display content, such as a mobile device.

Other objects, features and advantages of the present invention will become more apparent from the following description.

Preferred Embodiments for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described in detail with reference to drawings.

1 illustrates a cross-sectional structure of a display device according to an exemplary embodiment of the present invention. This display device is mounted in a mobile device, for example. The display element 20 is provided on the driving substrate 10. On the side where the display element 20 of the drive substrate 10 is provided, the sealing substrate 30 is disposed to face each other. The space between the drive substrate 10 and the sealing substrate 30 is completely filled by the intermediate layer 40.

The driving substrate 10 is made of an insulating material such as glass, for example.

The display element 20 may be, for example, a self-light emitting element such as an EL (organic light emitting element) or a PDP, or may be a liquid crystal element having a liquid crystal layer and a backlight.

The sealing substrate 30 seals the display element 20 together with the intermediate layer 40. The sealing substrate 30 may be made of a material transparent to the light from the display element 20, for example, glass or plastic resin such as acrylic or polymethylmethacrylate (PMMA).

The light guide part 50 is provided in the sealing substrate 30 facing each display element 20. The light guide portion 50 has an incident surface 51 on a surface facing the display element 20 and an exit surface 52 on the opposite side thereof. The light guide part 50 has a trapezoidal cross section, for example, widening from the incident surface 51 toward the exit surface 52. The side surface 53 is provided with a reflecting film 54. Accordingly, in this display device, the viewing angle is limited by limiting the acquisition direction of light, and the front luminance can be improved.

As the constituent material of the reflective film 54, for example, a single material or an alloy of a metal such as aluminum (Al) or silver (Ag) is possible. In addition, the reflective film 54 may be composed of a dielectric multilayer film.

In addition, the viewing angle α of the display element 20 satisfies the expression (1).

sinα≥n ₂ sin [atan {(p + a) / 2d}]

sinα≥n ₂ sinｕ ₂ = n ₂ sin (au ₁ / p)

In Equation 1, n ₂ is the refractive index of the light guide portion 50, a is the width of the incident surface 51, p is the width of the exit surface 52, d is between the incident surface 51 and the exit surface 52 U ₁ denotes the maximum angle of the light incident on the incident surface 51, and u ₂ denotes the maximum angle of the light emitted from the exit surface 52 after reflecting on the reflective film 54 on the side surface 53.

Viewing angle limitation means that all light is emitted within an angle within angle α in the air. To this end, the light emitted directly into the air without being reflected by the reflective film 54 and the light emitted into the air after being reflected by the reflective film 54 one or more times are simultaneously emitted within an angle within the angle α. It is necessary.

The first formula of Equation 1 shows a condition for light not directly reflected by the reflective film 54 to be emitted into the air within an angle α (light 1). That is, as shown in Fig. 3, when the maximum angle of light is θ, equation (2) holds. In addition, Equation 3 holds based on Snell's law. Therefore, the condition under which light is emitted at an angle within the range of angle α is expressed by the first formula of Equation (1).

tanθ = (p + a) / 2d

sinα≥n ₂ sinθ

The second formula of Equation 1 shows a condition for the light emitted in the air to fall within the angle α after being reflected by the reflective film 54 one or more times (light 2). That is, as shown in FIG. 4, the maximum angle u ₁ of the light incident on the incident surface 51 and the maximum angle u _{2 of} the light emitted from the exit surface 52 after being reflected by the reflective film 54 one or more times. Is expressed as in Equation (4). By applying this equation (4) to the light guide portion 50 taking into account the refractive index n ₂ and combining it with Snell's law, the second equation of equation (1) can be obtained.

au ₁ = pu ₂ ,

Where u ₂ is less than or equal to the critical angle.

In the second formula of Equation 1, u ₁ is the maximum angle of light incident on the light guide portion 50 having the refractive index n ₂ from the display element 20. In addition, since the discussion is made about the case where the luminance is set to almost zero in the case of 90 degrees or less by a resonator structure or a lens or the like described later, u ₁ is not 90 degrees.

In fact, the width a of the incident surface 51, the width p of the exit surface 52, and the distance d between the incident surface 51 and the exit surface 52 have a viewing angle α of, for example, 30 ° to 60 °. It is preferable to set so that. In addition, the distance d does not necessarily need to be equal to the thickness D of the sealing substrate 30. As shown in FIG. 2, the thickness D may be greater than the distance d. In addition, the refractive index of the intermediate layer 40 is n ₁ .

The portion surrounded by the reflective film 54 of the adjacent light guide portion 50 may be made of air, or at least a portion thereof may be embedded in the intermediate layer 40.

The intermediate layer 40 has an adhesive layer 41 made of, for example, a thermosetting resin or an ultraviolet curing resin. The driving substrate 10, the display element 20, and the sealing substrate 30 are joined to each other by the adhesive layer 41. In addition, the intermediate layer 40 may have a protective film (not shown), such as silicon nitride (SiNx) for protecting the display element 20, between the display element 20 and the contact bonding layer 41 as needed. .

FIG. 6 shows illumination analysis results when the viewing angle restriction is made by the light guide unit 50 with respect to a uniform surface light source. In addition, as an analysis condition, as shown in FIG. 7, the light emitting point 110 and the light receiver 120 corresponding to an eye are arrange | positioned at the distance L of 50 mm. As shown in FIG. 8, the light emitting point 110 has a 0.01 mm gap between a square uniform surface light source 111 having a side of 0.05 mm and a partition wall 112 having the light guide portion 50 described above. It is placed in place. The incidence surface 51 of the light guide portion 50 is square with one side of 0.05 mm, and the inclination angle of the side surface 53 is 17 degrees. In addition, the diameter phi of the light receiver 120 is 10 mm.

FIG. 9 shows the illumination analysis results under the same conditions as in FIG. 6 with respect to the case where the side surface of the light guide portion 50 is vertical, as shown in FIG. 10.

6 and 9, in FIG. 6, the light emitted from the light guide portion 50 is concentrated in the front direction than in FIG. 9, and it is understood that the effect of limiting the light acquisition direction is excellent. That is, the viewing angle can be limited by having the light guide portion 50 have a cross section that extends from the incident surface 51 toward the exit surface 52. In addition, the present inventors performed illumination analysis when the uniform surface light source 111 in which the partition 112 is not provided, ie, the light guide part 50 is not provided, is provided alone. As a result, in FIG. 6, it was confirmed that the cross-sectional intensity peak value of the emitted light was about 6 times as compared with the case where the uniform surface light source 111 was provided alone. Accordingly, it has been found that the front luminance can be increased by about six times by using the light guide portion 50, thereby reducing the power consumption to about one sixth. In this illumination analysis, the uniform surface light source 111 was used as the display element 20. However, almost the same result can be obtained also with the display element 20 provided with the resonator structure mentioned later.

11 shows an example of a specific configuration of such a display device. This display device is used as an ultra-thin organic light emitting color display device or the like. In the display device, on the driving substrate 10, between the TFT 11 and the planarization layer 12, the organic light emitting element 20R for generating red light, the organic light emitting element 20G for generating green light, and The organic light emitting element 20B for generating blue light is sequentially provided so as to form a matrix as a whole.

The gate electrode (not shown) of the TFT 11 is connected to a scanning circuit (not shown). The source and the drain (both not shown) are connected to the wiring 11B provided through the interlayer insulating film 11A made of, for example, silicon oxide or PSG (Phos-Silicate Glass). The wiring 11B is connected to the source and the drain of the TFT 11 through a connection hole (not shown) provided in the interlayer insulating film 11A and used as a signal line. The wiring 11B is made of, for example, aluminum (Al) or aluminum (Al) -copper (Cu) alloy. In addition, the structure of TFT11 is not specifically limited. For example, the structure may be a bottom gate type or a top gate type.

The planarization layer 12 is a base layer for planarizing the surface of the drive substrate 10 in which the TFTs 11 are formed, and for uniformly forming the film thickness of each layer of the organic light emitting elements 20R, 20G, and 20B. The planarization layer 12 is provided with a connection hole 12A for connecting the first electrode 21 and the wiring 11B of the organic light emitting elements 20R, 20G, and 20B. The planarization layer 12 is preferably made of a material having good pattern accuracy in order to form fine connection holes 12A. As a material of the flattening layer 12, and inorganic materials such as an organic material, or silicon oxide (SiO ₂₎ such as a polyimide.

In the organic light emitting elements 20R, 20G, and 20B, for example, a first electrode 21 as an anode, an insulating film 22, an organic layer 23 including a light emitting layer, and a second as a cathode The electrodes 24 are stacked in this order from the drive substrate 10 side. On the 2nd electrode 24, the above-mentioned protective film (not shown) is formed as needed.

In addition, in order to improve the luminous efficiency, the first electrode 21 also serves as a reflective layer and preferably has a high reflectance as much as possible. For example, the first electrode 21 has a thickness in the stacking direction (hereinafter simply referred to as "thickness") of 100 nm or more and 1000 nm or less, and includes chromium (Cr), gold (Au), platinum (Pt), and nickel ( It consists of a single substance or alloy of metal elements, such as Ni), copper (Cu), tungsten (W), or silver (Ag).

The insulating film 22 is for ensuring the insulating property of the 1st electrode 21 and the 2nd electrode 24, and making a light emitting area into a desired shape correctly. For example, the insulating film 22 is made of photosensitive resin. Openings are provided in the insulating film 22 corresponding to the light emitting regions. In addition, although the organic layer 23 and the 2nd electrode 24 are provided continuously on the insulating film 22, only the opening of the insulating film 22 generate | occur | produces light emission.

For example, as shown in FIG. 12, the organic layer 23 includes the hole injection layer 23A, the hole transport layer 23B, the light emitting layer 23C, and the electron transport layer (in order from the first electrode 21 side). 23D) is laminated | stacked. Among these, layers other than the light emitting layer 23C may be provided as needed. In addition, the organic layer 23 may differ in structure, respectively by the light emission color of organic light emitting element 20R, 20G, 20B. The hole injection layer 23A is for enhancing the hole injection efficiency and functions as a buffer layer for preventing leakage. The hole transport layer 23B is for enhancing the hole transport efficiency to the light emitting layer 23C. The light emitting layer 23C is for generating light due to the recombination of electrons and holes by applying an electric field. The electron transport layer 23D is for enhancing the electron transport efficiency to the light emitting layer 23C. In addition, an electron injection layer (not shown) made of LiF, Li ₂ O, or the like may be provided between the electron transport layer 23D and the second electrode 24.

The hole injection layer 23A of the organic light emitting element 20R is, for example, 5 nm or more and 300 nm or less in thickness, and has 4, 4 ', 4 "-tris (3-methylphenylphenylamino) triphenylamine ( triphenyl amine) (m-MTDATA) or 4, 4 ', 4 "-tris (2-naphthylphenylamino) triphenyl amine (2-TNATA). The hole transport layer 23B of the organic light emitting element 20R has a thickness of, for example, 5 nm or more and 300 nm or less, and is composed of bis [(N-naphthyl) -N-phenyl] benzidine (? -NPD). The light emitting layer 23C of the organic light emitting element 20R has, for example, a thickness of 10 nm or more and 100 nm or less, and is represented by 2, 6-bis [4- [N- (4) in the 8-kinolinol aluminum compound (Alq ₃ ). -Methoxyphenyl) -N-phenyl] amino styryl] naphthalan-1,5-dicarbonitrile (BSN-BCN) 40% by volume of the mixture. The electron transport layer 23 of the organic light emitting element 20R has, for example, a thickness of 5 nm or more and 300 nm or less, and is composed of Alq ₃ .

The hole injection layer 23A of the organic light emitting element 20G has a thickness of, for example, 5 nm or more and 300 nm or less, and is composed of m-MTDATA or 2-TNATA. The hole transport layer 23B of the organic light emitting element 20G has a thickness of, for example, 5 nm or more and 300 nm or less, and is composed of α-NPD. The light emitting layer 23C of the organic light emitting element 20G has a thickness of, for example, 10 nm or more and 100 nm or less, and is composed of 3 vol% of coumarin 6 (Coumarin6) mixed with Alq ₃ . The electron transport layer 23D of the organic light emitting element 20G has a thickness of, for example, 5 nm or more and 300 nm or less, and is composed of Alq ₃ .

The hole injection layer 23A of the organic light emitting element 20B has a thickness of, for example, 5 nm or more and 300 nm or less, and is composed of m-MTDATA or 2-TNATA. The hole transport layer 23B of the organic light emitting element 20B has a thickness of, for example, 5 nm or more and 300 nm or less, and is composed of α-NPD. The light emitting layer 23C of the organic light emitting element 20B has a thickness of, for example, 10 nm or more and 100 nm or less, and is composed of spiro 6Φ. The electron transport layer 23D of the organic light emitting element 20B has, for example, a thickness of 5 nm or more and 300 nm or less, and is composed of Alq ₃ .

The second electrode 24 has a thickness of, for example, 5 nm or more and 50 nm or less, and is composed of a single material or an alloy of metal elements such as aluminum (Al), magnesium (Mg), calcium (Ca), sodium (Na), and the like. It is. Among them, an alloy of magnesium and silver or an alloy of aluminum (Al) and lithium (Li) is preferable. The second electrode 24 is formed to cover all of the organic light emitting elements 20R, 20G, and 20B, and functions as a common electrode of the organic light emitting elements 20R, 20G, and 20B. In order to suppress the voltage drop of the second electrode 24, the auxiliary electrode 24A is preferably provided on the insulating film 22. The auxiliary electrode 24A is provided to fill the gap between the organic light emitting elements 20R, 20G, and 20B. The end part is connected to the stem type auxiliary electrode which becomes a generating line (not shown) formed in the periphery of the drive board | substrate 10 so that the area | region which organic light emitting element 20R, 20G, 20B is provided may be enclosed. . The auxiliary electrode 24A and the stem type auxiliary electrode serving as the bus bar (not shown) are configured in a structure in which a low resistance conductive material such as aluminum (Al) or chromium (Cr) is formed by a single layer or a laminate.

The second electrode 24 also has a function as a semi-transmissive reflective layer. That is, the organic light emitting elements 20R, 20G, and 20B have a resonator structure which resonates the light generated in the light emitting layer 23C and extracts light from the second end P2-where the light emitting layer of the first electrode 21 ( The end face on the 23C side is the first end P1, the end face on the light emitting layer 23C side of the second electrode 24 is the second end P2, and the organic layer 23 has a resonance portion. When the resonator structure is provided in this manner, light generated in the light emitting layer 23C causes multiple interference, and acts as a kind of narrowband filter. Thereby, the half bandwidth of the spectrum of the extracted light is reduced, and color purity can be improved. In addition, outside light incident from the side of the sealing substrate 30 may also be attenuated by multiple interference. By combining with a retardation plate, a polarizing plate, or a color filter which will be described later, the reflectance of external light in the organic light emitting elements 20R, 20G, and 20B can be made extremely small.

To this end, the optical distance L between the first end P1 and the second end P2 of the resonator satisfies Equation 5, and the resonant wavelength of the resonator (the peak wavelength of the spectrum of light to be extracted) is determined by It is desirable to match the peak wavelength of the spectrum. It is preferable that the optical distance L is actually selected to be the minimum value of the amount satisfying the expression (5).

(2L) / λ + Φ / (2π) = m

In Equation 5, L is the optical distance between the first end (P1) and the second end (P2), Φ is the phase shift (Φ1) and the second end (P2) of the reflected light generated at the first end (P1) Is the sum of the phase shift Φ 2 of reflected light generated at Φ = Φ 1 + Φ 2 (rad), and λ is the peak wavelength of the spectrum of light to be taken out from the second end P2 side, and m is an integer in which L is positive. Respectively. In addition, in Equation 5, the units of L and λ may be common, for example, nm is used.

The light guide part 50 mentioned above is provided in the sealing substrate 30. In addition, the side surface 53 of the adjacent light guide portion 50 need not be connected to an inverted V shape, as shown in FIG. 1, but may have a trapezoidal cross section.

In addition, for example, a wave plate 31 and a polarizing plate 32 may be bonded to the sealing substrate 30 on a surface opposite to the organic light emitting elements 20R, 20G, and 20B. As a result, reflection of external light is blocked, and sufficient contrast is maintained. In addition, a color filter (not shown) may be provided in the sealing substrate 30 instead of the retardation plate 31 and the polarizing plate 32. Thereby, brightness fall can be prevented, maintaining contrast.

The display device according to the embodiment of the present invention can be manufactured, for example, as follows.

13A to 15 show a method of manufacturing this display device in the order of steps. This manufacturing method has shown the case of manufacturing the display apparatus provided with organic light emitting element 20R, 20G, 20B as shown in FIG.

First, as shown in FIG. 13A, the TFT 11, the interlayer insulating film 11A, and the wiring 11B are formed on the drive substrate 10 made of the material described above. The planarization layer 12 which consists of the above-mentioned material is formed in the whole surface, for example by the spin coat method. Then, the planarization layer 12 is patterned into a predetermined shape by exposure and development. In addition, a connection hole 12A is formed and fired.

Next, as shown in FIG. 13B, the first electrode 21 made of the above-described material is formed by, for example, a sputtering method. Then, the first electrode 21 is formed into a predetermined shape by etching.

Subsequently, as shown in FIG. 14A, a photosensitive resin is applied over the entire surface of the drive substrate 10, and is molded by, for example, photolithography to form an opening in a portion corresponding to the first electrode 21. It installs and bakes, and the insulating film 22 is formed.

Subsequently, as shown in FIG. 14A, the auxiliary electrode 24A is formed over the entire surface of the driving substrate 10 on the insulating film 22, and selectively etched using, for example, a lithography technique. Patterning is carried out in a predetermined shape.

After forming the auxiliary electrode 24A, as shown in FIG. 14B, for example, by the vapor deposition method, the hole injection layer 23A, the hole transport layer 23B, and the light emitting layer 23C composed of the above-described thickness and material. The electron transporting layer 23D and the second electrode 24 are sequentially formed, and the organic light emitting elements 20R, 20G, and 20B as shown in FIG. 12 are formed. Subsequently, a protective film (not shown) is formed on the organic light emitting elements 20R, 20G, and 20B as necessary.

As shown in FIG. 15, the light guide portion 50 is provided on the sealing substrate 30 made of the above-described material. On the side surface 53 of the light guide portion 50, a reflective film 54 made of the above-described material is formed. The light guide part 50 can be formed using a stamper, when the sealing substrate 30 is comprised from plastic resin. The light guide portion 50 may be formed by grinding with a turning tool when the sealing substrate 30 is made of glass. The reflective film 54 may be formed by, for example, vapor deposition or sputtering.

Thereafter, an adhesive layer 41 is formed as the intermediate layer 40 on the organic light emitting elements 20R, 20G, 20B and a protective film covering the same, and the adhesive layer 41 and the sealing substrate 30 are bonded to each other. In that case, the surface in which the light guide part 50 of the sealing substrate 30 was formed is arrange | positioned as organic light emitting element 20R, 20G, and 20 microseconds. Finally, the retardation plate 31 and the polarizing plate 32 are bonded to the surface of the sealing substrate 30. Thus, the display device shown in FIG. 11 is completed.

In the display device according to the exemplary embodiment of the present invention, a predetermined voltage is applied between the first electrode 21 and the second electrode 24 in each of the organic light emitting elements 20R, 20G, and 20B, thereby emitting the light emitting layer 23C. An electric current is injected into the light, and holes and electrons recombine to emit light. This light is reflected multiplely between the first electrode 21 and the second electrode 24, and is extracted through the second electrode 24 and the sealing substrate 30. At this time, the cross section of the light guide portion 50 has a shape that extends from the incident surface 51 toward the exit surface 52, and the reflective film 54 is provided on the side surface 53, so that the total amount of light emission is the same. The emission angle range can be narrowed and concentrated in the front direction with respect to the emission surface 52. Therefore, the viewing angle α is limited and the front luminance is also improved.

Thus, in this embodiment, since the end surface of the light guide part 50 was formed so that it might become wider from the incident surface 51 toward the exit surface 52, and the reflective film 54 was provided in the side surface 53, By limiting the acquisition direction, the viewing angle α can be limited, and the front luminance can be improved.

In addition, since the energy consumed as the light emitted from the display element 20 can be used only by the viewer, the added value of ensuring the privacy of the display contents in the user without wasting power consumption. Occurs. In particular, in the case of a self-luminous display device such as the organic light emitting elements 20R, 20G, and 20B, by restricting the acquisition direction of the light emission, the luminance in the direction can be sufficiently maintained and the total amount of light emission can be reduced. Therefore, power consumption can be reduced.

As mentioned above, although this invention was demonstrated to an Example, this invention is not limited to the said Example, A various deformation | transformation is possible. For example, in the above embodiment, the case where the reflective film 54 is provided on the side surface 53 in order to form the side surface of the light guide portion 50 as the reflective surface has been described. By setting the difference, it is possible to generate total reflection at the side surface 53.

In the above embodiment, the side surface 53 is a slope plane and the light guide portion 50 has a trapezoidal cross section. However, the side surface 53 may be a curved surface.

In the above embodiment, a case has been described in which a resonator structure for multiple reflection of light generated in the light emitting layer 23C between the first end portion P1 and the second end portion P2 is formed, but the present invention does not have a resonator structure. Not applicable to organic light emitting elements 20R, 20G, and 20B.

In addition, the material and thickness of each layer demonstrated in the said Example, the film-forming method, film-forming conditions, etc. are not limited, It may be set as another material and thickness, or may be made into another film-forming method and film-forming conditions. For example, in the above embodiment, the first electrode 21, the organic layer 23, and the second electrode 24 are sequentially stacked on the driving substrate 10 from the driving substrate 10 side, and the sealing substrate ( Although the case where light was taken out from the light guide part 50 provided in 30 was demonstrated, on the drive board 10, the 2nd electrode 24, the organic layer 23, and the 1st electrode were reversed on the drive board 10. FIG. The 21 may be laminated sequentially from the driving substrate 10 side, and light may be taken out from the driving substrate 10 side. In this case, the light guide portion 50 may be formed on the driving substrate 10.

For example, in the said Example, although the case where the 1st electrode 21 was made into the anode and the 2nd electrode 24 was made into the cathode was demonstrated, the 1st electrode 21 will be reversed with the anode and cathode reversed. The cathode and the second electrode 24 may be used as the anode. In addition, the first electrode 21 is a cathode and the second electrode 24 is an anode, and the second electrode 24, the organic layer 23, and the first electrode 21 are driven on the driving substrate 10. It may be laminated sequentially from the (10) side, and light may be taken out from the driving substrate 10 side.

In addition, in the said Example, although the structure of organic light emitting element 20R, 20G, and 20B was demonstrated all concretely, it is not necessary to provide all the layers, and you may further provide another layer. For example, an oxide mixed film of chromium (III) oxide (Cr ₂ O ₃ ), ITO (Indium-Tin Oxide: Indium, and Tin) between the first electrode 21 and the organic layer 23. Or a thin film layer for hole injection, which is composed of a layer or the like. For example, the first electrode 21 can also be a dielectric multilayer film.

In addition, in the said embodiment, although the case where the 2nd electrode 24 was comprised from the semi-transmissive reflective layer was demonstrated, as for the 2nd electrode 24, the semi-transmissive reflective layer and the transparent electrode were sequentially from the 1st electrode 21 side. It may be a laminated structure. This transparent electrode is for lowering the electrical resistance of the semi-transmissive reflective layer and is made of a conductive material having sufficient light transmittance with respect to light generated in the light emitting layer 23C. As a material which comprises a transparent electrode, the compound containing ITO or indium, zinc (Zn), and oxygen is preferable, for example. This is because good conductivity can be obtained even when the film is formed at room temperature. The thickness of a transparent electrode can be 30 nm or more and 1000 nm or less, for example. In this case, the semi-transmissive reflective layer may be used as one end, and at the other end, a transparent electrode may be provided at a position opposite to the semi-permeable electrode, and the transparent electrode may be formed to form a resonator structure used as the resonator. After the resonator structure is provided, the organic light emitting elements 20R, 20G, and 20B are covered with a protective film, and the protective film is made of a material having the same refractive index as the material constituting the transparent electrode. Is preferable because it can be part of the resonator.

In addition, in the present invention, the second electrode 24 is composed of a transparent electrode, and the reflectance of the end surface on the opposite side to the organic layer 23 of the transparent electrode is increased so that the light emitting layer of the first electrode 21 is formed. The present invention can also be applied to the case where a resonator structure is formed in which the end face on the (23C) side is the first end and the end face on the opposite side to the organic layer of the transparent electrode is the second end. For example, the transparent electrode may be brought into contact with the atmospheric layer to increase the reflectance of the interface between the transparent electrode and the atmospheric layer, and the interface may be the second end. In addition, the reflectance at the interface with the adhesive layer may be increased, and this interface may be used as the second end. In addition, the organic light emitting elements 20R, 20G, and 20B may be covered with a protective film, the reflectance at the interface with the protective film may be increased, and the interface may be the second end.

Those skilled in the art will appreciate that various changes, combinations, sub-combinations, modifications, and the like may be made to the present invention without departing from the scope of the appended claims and their equivalents. I will understand.

In the display device according to the present invention, since the cross section of the light guide portion is widened from the entrance face to the exit face and the side face is composed of the reflection face, the emission angle range can be narrowed even if the total amount of light emission is the same. Concentrate on this exit surface in the front direction. Therefore, the viewing angle can be limited by limiting the acquisition direction of the light, and furthermore, the front luminance can be improved.

According to such an effect, the present invention is particularly suitable for a use in which it is necessary to secure the privacy of display contents, such as a mobile device.

Claims (6)

A display element, A cross section provided opposite the display element, having an entrance surface on the side opposite the display element, an exit surface on the side opposite to the display element, and a reflection surface on the side surface, and widening from the entrance surface to the exit surface; Having light guide part Including, The viewing angle α of the display element is sinα≥n ₂ sin [atan {(p + a) / 2d}] and satisfies all the conditions of sinα≥n ₂ sinｕ ₂ = n ₂ sin (au ₁ / p) The viewing angle α is 60 ° or less, Here, n ₂ is the refractive index of the light guide portion, a is the width of the incident surface, p is the width of the exit surface, d is the distance between the incident surface and the exit surface, u ₁ is the maximum of light incident on the incident surface And u ₂ represents a maximum angle of light emitted from the exit surface after reflecting from the reflection surface. delete The method of claim 1, A display device having a reflective film provided on the reflective surface. The method of claim 1, The display element is an organic light emitting element having an organic layer including a light emitting layer between a first electrode and a second electrode. 5. The method of claim 4, And the display element has a resonator structure for resonating light generated in the light emitting layer between a first end and a second end. The method of claim 1, The display element is provided on a drive substrate, a sealing substrate is disposed on the side where the display element is provided on the drive substrate, and the light guide portion is provided on the sealing substrate.

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